Several approaches have been employed or proposed to perform DNA sequencing. Among the various approaches, the nanopore approach has the great advantage of only allowing one base to pass a particular point at a time (if the orifice is small enough). It can also be highly processive (moving from one base to the next without “stuttering”) if the driving force is high enough.
Nanotubes have been considered as one way to implement a nanopore. For instance, the use of carbon nanotubes as nanopores through which DNA may be translocated electrophoretically has been described in T. Ito, L. Sun, R. M. Crooks, Chemical Communications, 1482 (2003) (Ref 1). Silica nanotubes have also been used as nanopores, as reported in R. Fan et al., Nano Letters 5, 1633 (September, 2005). A new approach for reading the sequence of a DNA molecule passing between electrodes on a nanopore using hydrogen bond-mediated tunneling signals has been proposed in J. He, L. Lin, P. Zhang, S. Lindsay, Identification of DNA base-pairing via tunnel current decay. Nano Letters 7 (12), 3854-3858, 2007. U.S. Pat. No. 6,821,730 discloses the use of carbon nanotube probes to sequence DNA. U.S. Pat. No. 6,627,067 discloses a method of translocating molecules through nanopores for sequencing purposes.
The aforementioned articles and patents are incorporated by reference to the extent necessary to understand the present invention.